1. Field of the Invention
The invention relates to an installation for recovery or conversion of hydraulic energy into another energy.
2. Brief Description of the Related Art
In the domain of energy conversion, in particular in the domain of the production of electrical energy from a waterfall, it is known to use a vertical - or horizontal-axis turbine of which the blades are disposed on the path of flow of the water in order to drive an apparatus, such as an alternator, in rotation. The adaptation of the energetic yield of the installation with respect to the flow of water which traverses it is generally controlled in order to obtain a constant speed of rotation of the shaft of the turbine hub, this making it possible to cause the alternator to function at stabilized exit speed and frequency. Such a servo-control of the functioning of the turbine is obtained by adjusting the orientation of flaps for admission of the water flow in the distributor of the turbine, such flaps being most often called xe2x80x9cguide vanesxe2x80x9d, and possibly by adjusting the orientation of the blades of the turbine about their pivot journals on its hub.
It is therefore necessary to use servo-motors for controlling the orientation of the guide vanes and the blades with respect to their respective pivot axes. This imposes the production of a gating ring whose diameter may be considerable.
French Patent 723 297 discloses a turbine of which the feed tank, free of guide vanes, has a spiral envelope, narrowing to form an anti-chamber for the rotor of a turbine. This spiral envelope or tank makes it possible to obtain a homogeneous circumferential feed of the turbine and to do without the use of guide vanes, which substantially simplifies the installation. However, the shape of this known tank is such that, in the event of considerable pressure prevailing therein, the tank or envelope tends to be deformed in a direction substantially parallel to the axis of rotation of the turbine. In practice, this deformation is such that the use of the turbines of this type has been limited to short falls, less than 2 meters.
Furthermore, in the known technique, the installations including a horizontal-axis turbine generally comprise a bulb in which are installed the alternator and its annexed equipment, this bulb being completely bathed by the water feed flow of the turbine. Such a bulb constitutes a confined space in which the implantation of the apparatus is relatively delicate and an access to this bulb should be provided for the operators and for the transmission of the electrical power and the information concerning the functioning of the installation, which, there again, imposes considerable servitudes.
It is a more particular object of the invention to overcome these drawbacks by proposing an installation for conversion of hydraulic energy not necessitating the use of distributors or of guide vanes, while presenting a mechanical resistance which is substantially increased with respect to the known turbines of the state of the art. Another object of the invention is to provide an installation in which the accessibility to the alternator and to its peripheral equipment is improved with respect to the installations comprising a bulb.
In this spirit, the invention concerns an installation for conversion of hydraulic energy into another energy, comprising a turbine, equipped with a wheel which rotates about an axis, and a tank feeding this turbine. The tank having, projecting on a plane globally perpendicular to this axis, an external spiral shape which forms a helico-convergent duct centered on this axis and convergent towards the turbine.
Helico-convergent is understood to mean that the duct is substantially in the form of a helix about the axis of rotation of the turbine, its outer envelope being convergent in the direction of this axis in the direction of flow, the transverse section of the tank reducing on the surface and approaching the axis in the afore-mentioned direction of flow.
Thanks to the helico-convergent nature of the duct formed by the tank, the duct extends both in a dimension parallel to the axis of rotation of the turbine and in a direction perpendicular to this axis, where it has an external, substantially spiral shape, which makes it possible to shape the flow of water in optimal manner in order to obtain a regular distribution of the flow of water at the blades of the turbine. The helico-convergent shape is such that the pressure prevailing in the tank is absorbed by walls thereof which extend, at least partly, parallel to the axis of rotation of the turbine and partly perpendicularly to this axis, being firmly connected to the other walls, with the result that they can absorb the forces of internal pressure of the duct without deformation.
According to advantageous but non-obligatory aspects of the invention, the installation incorporates one or more of the following characteristics:
the tank comprises a water admission part, for example of substantially rectilinear shape, of which a median axis forms an acute angle, preferably of the order of 45xc2x0, with the axis of rotation of the turbine. This inclined orientation of the water admission with respect to the axis of the turbine makes it possible to obtain both an axial acceleration and a centrifugal acceleration of the flow of water inside the tank, the centrifugal acceleration being countered by the reaction due to the outer partition of the tank.
The tank comprises an outer partition and an inner partition connected by at least one intermediate partition forming a lateral wall of the duct. These outer and inner partitions and this intermediate partition are firmly connected together, for example by welding in the case of partitions made of metal sheets, with the result that they efficiently oppose the radial forces resulting from the pressure prevailing inside the tank. In that case, the outer edge of the intermediate partition may be helico-convergent, centered on the axis of rotation and convergent in the direction of the opening of the duct formed around the turbine. Likewise in that case, two intermediate partitions may be provided, of which one constitutes an inner rib of the duct, the duct comprising two portions made between its outer and inner partitions, on either side of the inner rib. This inner rib therefore makes it possible to reinforce the rigidity of the tank further.
the tank forms, around the axis of rotation of the turbine, a volume accessible from outside the tank in a radial direction and surrounded by the duct. This volume makes it possible to house the shaft of the turbine and an alternator while it is easily accessible without having to traverse the duct, i.e. the flow of supply water of the turbine. The improved accessibility allows a better implantion of the alternator and facilitates the exploitation of the installation. This volume is advantageously bordered by the inner partition of the duct, this duct being inscribed in a cylinder with circular base coaxial to the axis of rotation of the turbine, at the level of a first part of this axis, and substantially truncated at the level of a second part of this axis.
the tank is formed by assembling metal sheets shaped as controlled surfaces. The tank of the invention may thus be manufactured by assembling surfaces that may be obtained by conventional operations of manufacture.
the tank comprises an outer partition substantially parallel to the axis of rotation of the turbine and defined between an upstream edge and a downstream edge, these edges having a helico-convergent shape centred on this axis, this outer partition being connected, at the level of its downstream edge, to a substantially truncated partition centred on the axis of rotation and of which a free edge, opposite the afore-mentioned downstream edge, surrounds or is adjacent to the opening of the duct, the afore-mentioned truncated surface being convergent in the direction of this free edge.